Sheng Yang created CLOUDSTACK-985:
-------------------------------------
Summary: Different MAC address for RvR caused issue in short term
network outrage
Key: CLOUDSTACK-985
URL: https://issues.apache.org/jira/browse/CLOUDSTACK-985
Project: CloudStack
Issue Type: Bug
Security Level: Public (Anyone can view this level - this is the default.)
Reporter: Sheng Yang
Assignee: Sheng Yang
Fix For: 4.1.0
The different MAC address for a pair of redundant router have issues when
short
time network outrage happened. When this happened:
1. BACKUP(r-2) cannot receive the broadcast from MASTER(r-1).
2. Then r-2 would announce it's MASTER after 3 seconds, and send gratuitous
ARP
to the gateway of public ip(usually a rack router).
3. The gateway of public ip would update it's ARP cache to associate the
public
ip of the network to the MAC of r-2.
4. In the meantime, r-1 still sending out VRRP broadcast(due to network
issue,
the broadcast never arrived at r-2), and acting as MASTER.
5. After network outrage, r-2 would receive the higher priority VRRP
broadcast
from MASTER again, then receded as BACKUP.
6. But the public gateway would still associate public ip with MAC of r-2,
thus
caused the issue. r-1 would no longer able to receive any packets from
public
network.
And there is no way for r-1 to send gratuitous ARP again, because it's
always
consider itself as MASTER, no state changed, and no hook existed for
receiving
lower priority broadcast.
I would introduce duplicate MAC address for RvR again.
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